Static eliminator for radioreceivers



Sept. 10, 1929. w. E.- GRIMM STATIC ELIMINATOR FOR RADIOREGEIVERS Filed May 11, 1926 INVENTOR TD AERIAL- ATTORNEYS Patented Sept. 10, 1929.

WATSON E. GRIMM, F CONCORDIA, KANSAS.

STATIC ELIMINATOR FOR RADIORECE IVERS.

Application filed May 11, 1926: Serial No. 108.342.

This invention relates to improvements in radio apparatus; one of the foremost ob jects being to provide a device for preventing undesirable electrical impulses, for example static electricity, from reaching the receiving set, various advantages appearing in the following specification, reference being had to the accompanying drawing in which Figure 1 is a perspective view illustrating the use of the device in connection with a radio receiver.

Figure 2 is a longitudinal section of the device.

Figure 3 is a detail cross section taken substantially on the line 3-3 of Figure 2.

Evervone who has had experience with radio r eceivers knows of the annoyance of interfering sounds such as are producedby the discharge of static electricity collecting upon the aerial, waves propagated by electrical apparatus of various kinds, etc. It is herein proposed to intercept the undesirable electrical impulses before they reach the receiving apparatus and to that end provislon is made of an air gap at which the unclesirable impulses may escape, and a surrounding metallic screen upon which said 1mpulses may impinge prior to conduction to the ground.

Reference is made to the drawing. The radio receiver R may be regarded as of any type. The aerial A, although of the loop or indoor type may also be regarded as of any well known kind. The aerial lead in wire 5 is indicated 1. The continuation 2 of the lead in wire is connected with the aerial binding post of the radio receiver. The ground G may consist of a radiator, water pipe or the like, and this ground is preferably independent' of the ground of the radio receiver (not shown).

The so-called eliminator 3 is connected in the lead-in wire 1-2, the respective wires being joined with the ends of a pair of coils of line copper wire 4 and 5. The wire 1 1S connected with the coil 4 at 21. The wire 2 is connected with the coil 5 at 23 and 22.

The first of the coils 4 is wound with approximately 100 of wire, while the second coil 5 is wound with approximately 150 of wire. The remaining end 20 of coil 4 is connected with bracket 13 whichsupports coil 1, wire 1 continues to {binding post 6 at base of disk 8, the wire 2 is. connected with a binding post 7 at the base of a. disk 9.55 These disks are mountedatlO upon the hard rubber or other base 11 and are not in electrical connection, excepting at the points 12' p I Plat-in um'or other suitable material isused for thepoints 12. These are mounted in confronting positionsupon the disks 8 and 9. These disks are-spaced apart a distance about one-eighth of an inch. ,The forms upon whichthe coils are, wound are mounted at 13 and 14 uponthe basell.

The whole device 1s covered by a" screen 15 of fine metallic wire preferably of brass, but it is anticipated that the wire could be substituted bya' metallic strip extending 7.0 over thetop. The screen is fasteneddown upon theinsulating base by suitable means, and has connected therewith a strip 16 carrying a binding post 17 with which the ground wire 18 is conveniently joined. The 7 lead-in wires 1 and 2 pass through suitable insulating bushings 19 where they enter the screen cover.

The device operates as follows: a

Current enters the device through the wire 1 which continues as coil 1 and is connected with the disk 8 at the binding post 6. As already stated, coil 4 is connected to wire 1 at point 21, the other end of the coil 4: being connected to the bracket which supports the coil at the point 20. The current then passes into disk 8 at 6,'through points at 12 into disk 9 and into wire 2 at the point 7. ire 2 passes around coil 5 for convenience and on to the antenna terminal of the radio apparatus. Coil Sis connected to wire 2 at points 22 and 23. This coil acts as a resistance unit, and the static seeking a low resistance path to ground passes from disks 8 and 9 into screen 15 across the 9 small space between the disks and the screen, and thus is grounded through wire 18 and does not reach the radio receiver.

The function of the coil 5 in particular is to block the setting up of disturbing osin conductor and antenna binding post of a cillations and prevent the passage thereof to the receiving set so that they are discharged across the air gap to the grounded screen 15.

I claim '1. In combination with the antenna leadradio receiver, a pair of coils interposed in said conductor having one end of each connected W1th ad acent partsof said conductor,

separated means constituting an air gap to Which the remaining ends of the coils'are connected, one of said coils acting as a resistance unit to cause the discharge vof electrical impulses across the gap, and a metallic screen fitted 'over said coils and air gap means, having a ground connectionfor conducting away said electrical impulses escaping'at said air'gap and being intercepted by the screen.

2. A device of the character described comprising a base, a pair of coils mounted 7 upon the base having one end of each connected With the components of an aerial lead-in conductor, one of the coils acting as a re'sistanceiunit, a pair 'ofupstanding elements mounted upon the base with Which the remaining ends of the'coil are connected, and constituting an" air gap from Which electrical'impulses are discharged by virtue of I said resistance unit, said elements having i confronting contact points in spaced relationship to each other, and a groundedv metallic screen receiving said impulses and covering the foregoing structure and being mountedupon the base. p

WATSON E. GRILiM. 

